Merge branch 'jt/upload-pack-v2-fix-shallow'

"git fetch" over protocol v2 into a shallow repository failed to fetch full history behind a new tip of history that was diverged before the cut-off point of the history that was previously fetched shallowly. * jt/upload-pack-v2-fix-shallow: upload-pack: clear flags before each v2 request upload-pack: make want_obj not global upload-pack: make have_obj not global